* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 1 NOTES – CHAPTER 9 (Brief) The Nervous System – LECTURE
Neurotransmitter wikipedia , lookup
Biological neuron model wikipedia , lookup
Embodied cognitive science wikipedia , lookup
End-plate potential wikipedia , lookup
Clinical neurochemistry wikipedia , lookup
Neuromuscular junction wikipedia , lookup
Optogenetics wikipedia , lookup
Aging brain wikipedia , lookup
Cognitive neuroscience wikipedia , lookup
Neuroplasticity wikipedia , lookup
Psychoneuroimmunology wikipedia , lookup
Microneurography wikipedia , lookup
Human brain wikipedia , lookup
Subventricular zone wikipedia , lookup
Synaptic gating wikipedia , lookup
Electrophysiology wikipedia , lookup
Haemodynamic response wikipedia , lookup
Metastability in the brain wikipedia , lookup
Neuropsychology wikipedia , lookup
Neuroscience in space wikipedia , lookup
Axon guidance wikipedia , lookup
Neural engineering wikipedia , lookup
Holonomic brain theory wikipedia , lookup
Molecular neuroscience wikipedia , lookup
Feature detection (nervous system) wikipedia , lookup
Single-unit recording wikipedia , lookup
Anatomy of the cerebellum wikipedia , lookup
Nervous system network models wikipedia , lookup
Development of the nervous system wikipedia , lookup
Channelrhodopsin wikipedia , lookup
Node of Ranvier wikipedia , lookup
Evoked potential wikipedia , lookup
Synaptogenesis wikipedia , lookup
Circumventricular organs wikipedia , lookup
Neuropsychopharmacology wikipedia , lookup
Neuroregeneration wikipedia , lookup
NOTES – CHAPTER 9 (Brief) The Nervous System – LECTURE NOTES I. Divisions of the Nervous System – two major divisions A. Central Nervous System (CNS) 1. brain 2. spinal cord B. Peripheral Nervous System (PNS) 1. Nervous structures that lie outside of the CNS 2. Two subdivisions a. Afferent division 1) transmits impulses from sensory organs to the CNS 2) Afferent fibers/neurons – nerve fibers that transmit action potentials from the periphery to the CNS b. Efferent (motor) division 1) transmits impulses from the CNS to effectors a) effectors include muscles or glands 2) Efferent fibers/neurons – nerve fibers that transmit action potentials from the CNS toward the periphery 3) Two subdivisions of Efferent division: a) Somatic Motor Nervous System – transmits impulses from CNS to skeletal muscles b) Autonomic Nervous System (ANS) – transmits from the CNS to smooth muscle, cardiac muscle, and glands; Can be divided into two subdivisions: i.) Sympathetic Nervous System – prepares the person for physical activity ii.) Parasympathetic Nervous System – activates function for daily maintenance of body (Example: digestion) II. Cells of the Nervous System A. Neurons – receive and transmit stimuli (action potentials) to effectors or other neurons; these are nonreproductive cells; have three (3) major parts: 1. Cell Body – contains the nucleus a. site of protein synthesis; if axon is separated from cell body, it will die because no new proteins are being made for it b. Nissl bodies – areas of rough ER concentration 2. Dendrites – short, often highly branched cytoplasmic extensions coming off the cell body; a. usually several b. carry action potentials (impulse) to the cell body 3. Axons – long cell process extending from the cell body a. only one per neuron b. carries action potential away from the cell body c. collateral axons – branches off axon 1 d. myelin sheath – highly specialized insulating layer of cells around some axons 1) Specialized wrappings around axon; made of fat; is white in color 2) Excellent insulator and conductor; prevents almost all ion flow through the cell membrane 3) Nodes of Ranvier – gaps or indentations between neurolemmocytes; allow for the nerve impulses to travel faster; allows ions to flow easily & help action potentials develop and travel 4) Mylenated axons conduct action potentials faster a) Salutatory conduction – impulse jumps from node of Ranvier to node of Ranvier 5) Uses less energy because less ions travel across membrane B. Neuroglia or glial cells – non-conducting cells within the nervous system 1. more numerous than neurons 2. retain ability to divide 3. Four types: a. Astrocytes – star-shaped cells 1) major supporting cell in the CNS 2) attached neurons to blood vessels 3) blood-brain barrier – permeability barrier between blood & nerve cells b. Ependymal cells – line fluid-filled cavities in CNS 1) produce cerebrospinal fluid or help move this fluid through the CNS c. Microglia – help remove bacteria & cell debris from CNS d. Neurolemmocytes - cells that produce myelin sheaths 1) Oligodendrocytes– cells with many dendries; surround axons in CNS 2) Schwann cells - Oligodendrocytes in PNS C. Organization of Nervous Tissue 1. Gray Matter – groups of neuron cells bodies & their dendrites a. Cortex- gray matter on the surface of the brain b. Nuclei- clusters of gray matter deeper within the brain c. Ganglion – in PNS, cluster of neuron cell bodies 2. White Matter – bundles of parallel axons with their myelin sheaths a. Nerve tracts – conduction pathways formed by white matter of the CNS; propagate action potentials from one area of CNS to another b. Nerves – bundles of axons and their connective tissue sheaths in PNS III. Transmission of action potentials in nervous system A. Synapse – the junction at which the axon of one neuron interacts with the dendrites of another neuron or an effector organ (muscle or gland) 1. Presynaptic terminal – end of the axon 2 2. Synaptic cleft – space separating the presynaptic & postsynaptic terminals 3. Neurotransmitters – chemical substances released by presynaptic terminal in response to an action potential a. Either allow or inhibit the impulse to cross the synaptic cleft to the postsynaptic membrane 4. Postsynaptic membrane – membrane of the dendrite or effector B. Reflexes – involuntary reaction in response to a stimulus applied to the periphery & transmitted to the CNS 1. allows a quicker response than would be possible if conscious thought was involved 2. Reflex arc – neuronal pathway by which a reflex occurs a. basic functional unit of the nervous system b. smallest, simplest pathway capable of receiving a stimulus and yielding a response c. Five basic components 1) sensory receptor 2) afferent or sensory neuron 3) association neurons 4) efferent or motor neuron 5) effector organ d. most involve the spinal cord or brainstem & not higher brain centers e. Examples: 1) Withdrawal 2) knee jerk IV. Central Nervous System (CNS) – consists of brain and spinal cord A. Include the four (4) major parts of the brain 1. brainstem 2. diencephalons 3. cerebrum 4. cerebellum B. Brainstem 1. Connects brain to spinal cord 2. Has many nuclei involved in vital body functions a. damage to small areas of the brainstem can cause death 3. Has three major areas including medulla oblongata, pons, and midbrain: a. Medulla oblongata 1) most inferior part of brainstem & continues inferiorly with spinal cord 2) Contain nuclei with specific functions: a) regulation of heart rate & blood vessel diameter b) breathing b. Pons - name means “bridge” 1) superior to medulla oblongata 2) relays information between cerebrum and cerebellum c. Midbrain 3 1) 2) 3) 4) superior to pons smallest region in the brainstem contains centers for auditory & visual pathways substantia nigra – black mass that regulates general body movements 4. Reticular Formation a. group of nuclei scattered throughout the brainstem b. plays a major role in arousing & maintaining consciousness and in regulating the sleep/wake cycle c. damage to may cause a coma C. Diencephalon 1. part of the brain between the brainstem and the cerebrum 2. made up of thalamus, epithalamus, & hypothalamus a. thalamus 1) largest part of diencephalons 2) Functions: a) passes sensory input from body to cerebral cortex b. epithalamus 1) small area superior and posterior to the thalamus 2) Functions: a) controls emotional & visceral response to odors b) contains pineal body – an endocrine gland i.) influences the onset of puberty c. hypothalamus 1) most inferior part of diencephalons 2) Functions: a) plays a major role in maintaining homeostasis b) controls body temperature, hunger, & thirst 3) infundibulum – funnel-shaped stalk of the hypothalamus that extends to the pituitary gland a) controls secretions of hormones from pituitary gland D. Cerebrum 1. largest part of the brain a. centers for thought process, memory, and voluntary muscle action 2. divided into left & right hemispheres by a longitudinal fissure a. Right hemisphere 1) Receives information fromand controls left side of the body 2) more creative abilities like music, art, drama, literature, etc b. Left hemisphere 1) controls right side of the body 2) involves analytical, logical skills like math and science and speech c. Commissures – connections between hemispheres where sensory information is shared made of broad bands of nerve tracts 4 1) corpus callosum – largest commissure a) a broad band of nerve tracts at the base of the longitudinal fissure 3. Gyri – numerous folds on the surface of each hemisphere; increase the surface area of the cortex 4. Sulci – shallow grooves between gyri 5. Fissure – deep grooves between areas of brain 6. Divided into four (4) lobes (sections) named for the skull bones overlying them a. Frontal lobe – functions voluntary motor functions, motivation, aggression, mood, and olfactory reception b. Parietal lobe – principal center for reception and evaluation of most sensory information such as taste, pain, touch, temperature, and balance 1) Central sulcus – prominent sulcus separating the frontal and parietal lobes c. Occipital lobe 1) function in reception & integration of visual input 2) not distinctly separated from other lobes d. Temporal lobe 1) evaluates olfactory and auditory input 2) plays a role in memory E. Cerebellum – “little brain” 1. Cortex is made of gray matter; gyri are smaller than cerebrum 2. Internally consists of nuclei and nerve tracts 3. Functions: a. comparator – compares the intended movement with the actual movement and adjusts for any discrepancies 1) alcohol inhibits function of cerebellum b. balance, maintenance of muscle tone, & coordination of fine motor movement c. Accomplishes “learned” movements automatically after they have been initiated by cerebrum 1) Ex. learning to ride a bicycle F. Spinal cord 1. extends from foramen magnum to second lumbar vertebra 2. made up of central gray area in the shape of an “H” surrounded by white matter 3. axons make up the white matter and are grouped by function in tracts or pathways G. Meninges- connective tissue layers surrounding and protecting the brain and spinal cord 1. Layers: a. Dura mater – means “tough mother” 1) outermost & thickest layer 2) attached to the periosteum of skull (in the cranium) 5 3) surrounded by epidural space (in spinal cord) 4) extends into longitudinal fissure between cerebral hemispheres & between cerebrum & cerebellum. b. Arachnoid layer – “spiderlike or cobwebs” 1) thin, whispy later that looks like spider web c. Pia mater – “affectionate mother” 1) tightly bound to surface of the brain and spinal cord 2) thin & transparent H. Ventricles - fluid- filled cavities 1. Lateral ventricles - (2) located in each cerebral hemisphere; relatively large cavities I. Cerebrospinal fluid (CSF) 1. bathes the brain and spinal cord 2. provides a protective cushion around the CNS 3. Choroid Plexus – a specialized structure of ependymal cells located in the lateral and fourth ventricles; produces cerebrospinal fluid 4. fills brain ventricles, the central canal of the spinal cord, and the subarachnoid space V. Peripheral Nervous System (PNS) A. consists of all the neurons located outside the brain and spinal cord B. Two structural parts of PNS: 1. Cranial nerves – 12 pairs; two major types are sensory (afferent) and motor (efferent) nerves 2. Spinal nerves – 31 pairs; categorized by the region of the vertebral column from which they emerge a. Example: C = cervical and number = C-1 6